Borates play an important role in forestry - preventing fungal attack in both living trees and cut lumber, and providing an essential micronutrient to managed forestlands.

Fomes Control

Heterobasidion annosum, also known as fomes, is the most devastating disease affecting conifers, and can be found in most if not all managed coniferous forests in the Northern Hemisphere. Freshly cut stumps are infected during thinning and clear felling. Fomes can thrive and remain infectious for decades, and has been recorded in stumps up to 60 years after felling. The fungus, which causes root rot, infects living trees through interconnecting root systems. The disease kills trees and causes commercially significant decay of felled logs. The spores produced by the fungus are so small, even light breezes can carry them 100 meters or more. Fomes attacks all coniferous tree species but causes the greatest damage to pine, spruce and fir.

Borates protect forests from this organism. When applied to the surface of stumps they prevent the fungus from colonizing and infecting surrounding trees. One of seven essential micronutrients necessary for all plant growth, borates provide an added benefit by fertilizing forestlands.

Sapstain control

Sapstain, also known as blue stain, is a discoloration of wood caused by fungal attack. Generally, it is blue-black but it can be brownish or purple, depending on the fungus responsible. In severe cases, the stain penetrates the entire sapwood. Sapstain does not necessarily weaken the wood but it does spoil the appearance, reduces market value and is often associated with incipient decay. Softwoods, particularly pines, are more generally susceptible to sapstain than hardwoods.

Sapstain fungi attack a tree soon after it is felled and develop quickly, given suitable conditions. Preventive treatment should be applied within twenty-four hours, making chemical dips or sprays the most effective treatments. Kiln drying or good air seasoning can prevent attack but it is rarely possible to expedite either operation to eliminate the threat. The chemical dip safely bridges the gap between felling, milling and drying.

The earliest use of borates to prevent wood fungus attack focused on developing treatments against sapstain. While borates alone can control staining organisms in many circumstances, very severe cases call for borates in conjunction with other anti-sapstain chemicals to enhance their performance. Specific organic fungicides have proven to give the greatest benefits when used in conjunction with borates. Examples include formulations using didecyl dimethyl ammonium chloride (DDAC), 3-ido-2- propynylbutylcarbamate (IPBC) and azole products. Borates also function as buffers - reducing degradation of some organic fungicides and preventing discoloration associated with some copper systems.